Even Instagram’s own API (the interface developers use to build third-party apps) respects this privacy setting. No legitimate developer can build a “private viewer” because Instagram actively blocks such attempts.
Attempting to use automated scrapers or unauthorized third-party apps violates Instagram's Community Guidelines. If Instagram detects this activity originating from your IP address or account, it can result in a permanent ban. Safe and Legitimate Ways to See Private Profiles private instagram viewer danlwd full